Posttraumatic stress disorder (PTSD) has been shown to predict later self-reported sexual risk behavior, yet behavioral research is lacking in this area. The present study investigated the impact of PTSD severity on negotiation and interpersonal skills effectiveness in simulated high-risk sexual situations among 368 inner-city women. Participants engaged in role-play scenarios involving (1) refusing sexual intercourse without a condom, (2) abstaining from drinking before sex, and (3) refusing sex until both partners were tested for HIV. Interviews were audiotaped and rated along dimensions of negotiation effectiveness by raters for whom participant ethnicity was masked. Hierarchical linear regression analyses were conducted to investigate the effect of PTSD and ethnicity on 4 theoretically derived skill sets: (1) assertiveness, (2) using health and preparedness skills, (3) social joining skills, and (4) higher order negotiation skills. Generally, results indicated that PTSD severity predicted poorer rated negotiation effectiveness among European Americans, but not African Americans. African Americans' expectations that may prepare them for facing more hardship may help explain ethnic differences.